Flexible displays can benefit from being sealed at the edges. An edge seal that seals the top and bottom substrates of a flexible display provides protection for the display from delamination, environmental contaminants and leakage of display materials such as liquid crystal. The edge seal can either be an adhesive or a laser weld of the display edge. The adhesive can either be applied internally within the display substrates or externally.
Currently, flexible displays can be properly sealed during the laser singulation process where the display panel is separated from the web line. According to U.S. Patent Application Publication 2007-0277659, utilizing and controlling the infra-red heat generated by a laser during display singulation has been shown to sufficiently seal the display by welding the top and bottom substrates in the presence of liquid crystal between the two plastic substrates.
In some situations such as when a portion of the bottom or top substrate has to be exposed such as in the creation of a ledge, this process cannot be used, and is supplemented by other processes. One such process is the application of an external adhesive after the ledge is exposed. In this process, the regions of the display closest to the ledges are prone to delamination. In addition, applying the gasket externally requires the displays to be singulated prior to sealing, this leads to increased processing time and yield losses due to delamination prior to gasket application.
In some cases using a method such as that described in U.S. Patent Publication 2009-0153756, an internal gasket is present before liquid crystal is filled between the substrates. Utilizing this method only seals two edges of the display.